In conventional telecommunications networks that support mobile subscribers, one or more network entities maintain what is referred to as subscriber information, which may include the identity of the subscriber, the services that are available to the subscriber, and the current location of the mobile subscriber. In conventional telecommunications networks, certain network entities are responsible for maintaining subscriber information and for making that information available when needed. For example, global system for mobile communications (GSM) networks include a home location register, or HLR, which maintains information about subscribers to a mobile network. In Internet protocol media subsystems (IMS) networks, some of the same or similar functions are performed by a home subscriber server, or HSS. For simplicity, a network entity responsible for maintaining subscriber information is hereinafter generically referred to an HLR/HSS.
Access to subscriber information is vital to the operation of a mobile telecommunications network. Other network elements, such as mobile switching centers (MSCs) and call session control functions (CSCFs) communicate mobile subscriber status information to the HLR/HSS nodes using various signaling protocols, including GSM/IS-41 mobile application part (MAP), Diameter, and others. Example subscriber information management messages include MAP and Diameter UpdateLocation messages, Diameter user data request (UDR) messages, Diameter profile update, Diameter location information request (LIR) messages, Diameter server assignment request (SAR) messages, and MAP signal routing information (SRI) messages. These messages carry, among other things, information that identifies the current serving MSC or CSCF. The HLR/HSS is also configured to provide mobile subscriber information to a requesting MSC or CSCF.
There are disadvantages associated with conventional telecommunications networks that support mobile subscribers. In conventional networks, mobile subscribers are assigned or homed to a single subscriber information management node, such as an HLR or HSS. If the HLR/HSS nodes in a mobile communications network become unreachable, isolated, or otherwise unavailable, major service disruptions are possible and likely. What is needed, therefore, is a system and method for minimizing the negative impact of loss of access to subscriber information management information, such as may occur as a result of HLR/HSS network element isolation events in a mobile telecommunications network.
One conventional approach to overcome the disadvantages stated above has been to create an entity, called a gateway location register, or GLR, that copies mobility management messages, caches all of the information contained within the mobility management messages, and responds on behalf of the HLR/HSS when possible, in order to reduce the workload on the HLR/HSS. This conventional approach suffers the disadvantage that the GLR always responds on behalf of the HLR/HSS, even if the HLR/HSS is operational. What is needed is a system or method which provides backup service, responding only when the HLR/HSS is not operational.
Another conventional approach to overcome the disadvantages stated above has been to distribute the function of an HLR/HSS across a bank of nodes, where each individual HLR/HSS services a particular subset of subscribers, and to place a distribution function between the bank of nodes, where the each subscriber is routed to that subscriber's HLR/HSS. This conventional approach suffers the disadvantage that failure of a particular HLR/HSS causes a loss of service to whichever subscribers had been assigned to that HLR/HSS. Rather than protect against loss of service, this approach limits loss of service to a subset of subscribers rather than having all subscribers lose service. However, if the distribution function fails, all subscribers lose service anyway. What is needed is a system or method which can supplement this conventional approach by providing backup service for both any individual HLR/HSS that may fail, and also provide backup service in case the distribution function fails as well.
Another conventional approach to overcome the disadvantages stated above involves load sharing across multiple HLR/HSS nodes, where messages are distributed across the nodes to reduce the load on any individual node. This conventional approach suffers the disadvantage that each node must contain a full copy of the subscriber information database. This gives rise to overhead required to keep all databases in synchronization with each other. This approach suffers the additional disadvantage that a corrupted entry in one node's database is quickly replicated across all nodes' databases, rendering them all susceptible to the same kind of database corruption. What is needed is a system or method which stores information independently from the HLR/HSS nodes and is thus isolated from corruption of any one of the HLR/HSS nodes.
Accordingly, in light of these disadvantages, there exists a need for systems, methods, and computer readable media for using a signaling message routing node to provide backup subscriber information management service.